i rarely touch battle/defensive unless bloodrage is up. i use battle for Tclap on melee, and rend/overpower on rogues, but if i have a lot of rage (30+) i dont worry about swapping stances unless i can get rid of most of that rage before i swap.
for defensive, its usually an intercept > def > bloodrage > disarm combo on rogues, or more rarely using defensive to weather focus fire while keeping an eye on my team to intervene someone far back (and thus get out of FF for a little while).
im 33/28 btw, ms with second wind and flurry. id say 80-90% of the time im in zerker stance.